Spectroscopic modulation of multifunctionalized quantum dots for use as biological probes and effectors

Abstract

Multifunctional nanoparticles, quantum dots (QDs) are being developed as uniquely sensitive tools for elucidating the (bio)chemical and (bio)physical molecular mechanisms underlying functional states, i.e. the molecular physiology, of biological cells and organisms. Here we present a group of strategies and examples for (i) controlling the spectroscopic properties of QDs via Fluorescence Resonance Energy Transfer (FRET); (ii) determining the emission spectra of individual QDs in a population with an imaging spectrograph (ASI SpectraCube); and (iii) employing such liganded QDs as nano-probes in cellular studies of signal transduction.

Photoswitchable Fluorescent Nanoparticles: Preparation, Properties and Applications

“…Various QDs-based nanoparticles exhibiting photoswitchable fluorescence features were fabricated in Medintz's group, [86,87] Li's group, [88] and others. [89][90][91][92] Thus, the challenge to modulate the fluorescence of QDs shifts the focus to nanoparticle surface modification. Scheme 2 illustrates a general approach to construct composite nanoparticles via a typical surface modification approach.…”

Imaging molecular interactions in living cells by FRET microscopy

“…Such a property potentiates deterministic 'J engineering' (Equation 1) or indirect reporting of the state of a dark acceptor via the fluorescent donor (Equation 2). Other examples of molecular photoswitches [31] are photoconvertible VFPs [32,33 ,34-39], caged acceptors [40], photochromic diheteroarylethenes devised for photochromic FRET [1,[41][42][43], and photochromic spiro-naphthoxazines/benzopyrans devised as modulators of molecular structure and function [44]. Such molecules can be exploited for achieving super-resolution by non-linear optical imaging (STED; [45]).…”

“…For this reason, QDs are easily detected and identified visually and by electronic imaging, providing single molecule sensitivity, positional super-resolution [50], and confirmation of molecular identity (e.g. of substances to which they are conjugated), as a consequence of their blinking behavior and distinctive narrow emission spectra [43]. As FRET donors, QDs also benefit from their large absorption cross-section that increases continuously from their narrow emission bands to the UV.…”

“…As FRET donors, QDs also benefit from their large absorption cross-section that increases continuously from their narrow emission bands to the UV. Thus, despite their relatively large size [1], requiring close proximity of the acceptor(s) to the nanoparticular surface, QDs function efficiently as FRET donors in many bioanalytical and imaging applications [41,43,51,52 ]. One can anticipate the development of QDs with smaller stabilization-conjugation coats for enabling FRET probing at locations removed from the particle surface.…”

Supramolecular Strategies To Construct Biocompatible and Photoswitchable Fluorescent Assemblies

“…In fact, the structural and electronic changes, accompanying their photoinduced and reversible transformations, can be engineered to control the emission of complementary fluorophores. − Specifically, fluorescent and photochromic components can be integrated within a common covalent skeleton, and the emission of the former can be modulated by interconverting the latter under optical control. Accordingly, numerous examples of fluorophore−photochrome dyads have already been developed, − and their operating principles for fluorescence modulation have recently been extended to nanostructured constructs − and extensively reviewed . In most instances, electron and energy transfer processes dominate the excited-state dynamics of these multicomponent assemblies and dictate their emission signature.…”